Solder material test method and apparatus, control program and computer-readable recording medium

ABSTRACT

Provided is a solder material test method that reduces labor and time and is preferred in operation hygiene. Detected are a first intensity at a particular wave number of infrared radiation reflected from a test-sample solder material by illuminating light to the test-sample solder material and a second intensity at the particular wave number of infrared radiation reflected from a comparative-sample solder material by illuminating light to the comparative-sample solder material. Depending upon the first and second intensities detected, intensity differences and ratios are determined. Those may be absorbance differences or intensities of between an infrared radiation absorbance to test-sample solder material and an infrared radiation absorbance to comparative-sample solder material. From the intensity difference, intensity ratio, absorbance difference and absorbance ratio, the test-sample solder material is tested for deterioration degree relatively to the comparative sample.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for testing asolder material for deterioration degree.

2. Description of the Related Art

On the production line of printed boards, electronic components aremounted onto the board by performing a printing process to print asolder material to a board, a mounting process to mount an electroniccomponent onto the printed solder material and a reflow process to fixthe electronic component on the board by soldering.

In the printing process, the solder material is put on the surface of ametal mask placed on the board. The metal mask is formed with an openingcorresponding to a wiring pattern. The solder material on the metal masksurface is pushed and rotationally moved by a movable squeegee.Furthermore, the solder material being rotationally moved is squeezedout of the opening onto the board by the urging force of the movablesqueegee. Based on this process, the solder material is printed to theboard (see paragraph [0011] in JP-A-5-99831).

The metal mask is in continuous use for a number of boards, in a statewhere the same solder material is rested thereon. Accordingly, thesolder material is rotationally moved by the movable squeegee repeatedlyeach time printing is performed. The solder material graduallydeteriorates due to rotational movement, and the deteriorated soldermaterial constitutes a factor causing defects on the printed board.

For this reason, when the solder material on the metal mask is analyzedin-line for deterioration degree and the solder material is deterioratedsignificantly, it is quite important to replace the solder materiallying on the metal mask. In addition, before supplying a solder materialonto the metal mask, it is important to analyze the deterioration degreeof the solder material to supply and check whether or not there is adeterioration in the solder material before it is supplied.

Here, the solder material has a viscosity, oxidation degree and reducingpower that serves as an index in evaluating the deterioration degreethereof. The reason the viscosity, oxidation degree and reducing poweris used as an index is because of the following.

It is known that, as solder material deteriorates, its viscosityincreases to proceed oxidation and lower the reducing power. Herein, itis also known that, when a highly viscous solder material is printed onthe board, defects such as “breakages” or “blurs” readily occur on theboard thus printed. Meanwhile, it is also known that, in case anoxidized solder material is printed to the board, inferiorities such as“solder balls” or “solder unfused” readily occur on the post-reflowboard. Furthermore, it is also known that, when solder material which islowered in reducing power is printed to a board, such an inferiority as“wettability reduction” readily occurs on the post-reflow board.

Namely, the viscosity, oxidation degree and reducing power of a soldermaterial is correlated to the occurrence rate of printed boardinferiorities. For this reason, the viscosity, oxidation degree andreducing power of a solder material serves as a significant index inevaluating the deterioration degree of a solder material.

Conventionally, there are various methods to analyze the deteriorationdegree of solder material, as exemplified in JP-A-5-99831 (date opened:Apr. 23, 1993), JP-B-8-20434 (date published: Mar. 4, 1996) andJP-A-10-82737 (date opened: Mar. 31, 1998).

JP-A-5-99831 discloses a method to measure the viscosity of a soldermaterial depending upon a velocity of a solder material flowing on asqueegee surface. However, this method can measure the viscosity of asolder material only when driving the squeegee. Thus, there is a problemthat the test sample is limited to a solder material being used in aprinting process.

Consequently, JP-B-8-20434 discloses a method to measure the acid degreeof a solder material (flux) by conducting a titration by use of a soldermaterial sampled. However, in this method, there encounters a problemthat labor and time is required in conditioning a reagent.

Meanwhile, JP-A-10-82737 discloses a technique to measure the surfaceoxidation rate of a solder material according to ultraviolet-rayphotoelectron spectroscopy. However, this method uses ultravioletradiation that is harmful to the human body, and hence is not preferredin view of operation hygiene.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a solder materialtest method and apparatus where labor and time are reduced in operation,and hence is preferred in operation hygiene.

In order to achieve the object, a solder material test method in thepresent invention includes: a first detecting step of detecting a firstintensity at a particular wave number of infrared radiation reflectedfrom a test-sample solder material by illuminating light to thetest-sample solder material; a second detecting step of detecting asecond intensity at the particular wave number of infrared radiationreflected from a comparative-sample solder material by illuminatinglight to the comparative-sample solder material; and a test step oftesting a deterioration degree of the test-sample solder materialrelatively to the comparative-sample solder material, depending upon thefirst and second intensities detected.

It is known that a solder material of good quality is low in viscosityand oxidation degree, but high in reducing power wherein, when thesolder material deteriorates, a viscosity/oxidation degree increases andreducing power decreases. Accordingly, the deterioration degree of asolder material can be determined from one of a viscosity, an oxidationdegree and a reducing power of the solder material.

The present inventors have considered a technique that is different fromthe existing technique but can analyze at least one of viscosity,oxidation degree and reducing power of a solder material. As a result ofeager devising, the present inventors have found that a solder materialcan be analyzed for at least one of viscosity, oxidation degree andreducing power by use of infrared spectroscopy.

Below is detailed the reason why a solder material can be analyzed forviscosity, oxidation degree or reducing power by an infraredspectroscopy.

Where a solder material is in continuous use or exposed to the externalair, the metal contained in the solder material oxidizes and the acidcontained (e.g. carboxylic acid) turns into a salt. Namely, when asolder material is used and is continuously exposed to the exterior air,the contained metal oxide increases, the contained acid decreases andthe contained salt increases in the solder material.

The metal oxide increase raises the solder-material oxidation degree,the salt increase enhances the solder-material viscosity and acidcontent decrease lowers the solder-material reducing power.

For this reason, in case a test-sample solder material is to be analyzedfor the content of metal oxide, acid and salt, the relevant soldermaterial can be tested for viscosity, oxidation degree and reducingpower, and eventually for solder-material deterioration degree. Namely,the content of metal oxide, acid and salt in a solder material isindicative of a deterioration degree (viscosity, oxidation degree andreducing power) of the solder material.

Here, the present inventors have realized that at least one of metaloxide, acid and salt contents can be analyzed by infrared spectroscopy,thus reaching a realization of the invention.

Specifically, the invention detects a first intensity at a particularwave number of infrared radiation reflected from the test-sample soldermaterial due to illumination of light to the test-sample soldermaterial, and a second intensity at the particular wave number ofinfrared radiation reflected from the comparative-sample solder materialdue to illumination of light to the comparative-sample solder material.

Here, in accordance with the content of metal oxide, acid and salt in asolder material, the solder material changes in absorption of infraredradiation at a particular wave number, thus changing the intensity atthe particular wave number of infrared radiation reflected by the soldermaterial. This is because the metal oxide, acid and salt contained inthe solder material each have a property to absorb infrared radiation ata wave number band specified.

Accordingly, depending upon a first intensity at a particular wavenumber of infrared radiation reflected by a test-sample solder materialand a second intensity at the particular wave number of infraredradiation reflected by a comparative-sample solder material, thetest-sample solder material can be analyzed for metal oxide, acid andsalt contents relative to those of the comparative-sample soldermaterial. This makes it possible to test relatively the test-samplesolder material for viscosity, oxidation degree and reducing power.Accordingly, the deterioration degree (viscosity, oxidation degree andreducing power) of the test-sample solder material can be testedrelatively to the comparative-sample solder material.

In the solder material test method of the invention, the illuminationlight to the solder material may be infrared radiation at the particularwave number or light including infrared radiation at the particular wavenumber.

The solder material test method of the invention shown in the above doesnot require a titration as disclosed in JP-B-8-20434, thus furtherreducing the operational labor and time than the method in JP-B-8-20434.The solder material test method of the invention shown in the above doesnot use ultraviolet radiation, and hence is preferred rather than themethod of JP-A-10-82737, in respect of operational hygiene.

Meanwhile, in order to achieve the foregoing object, a solder materialtest apparatus in the invention comprises: a light source thatilluminates light to a test-sample solder material and acomparative-sample solder material; intensity detecting means thatdetects a first intensity at a particular wave number of infraredradiation reflected from the test-sample solder material due toillumination of the light, and a second intensity at the particular wavenumber of infrared radiation reflected from the comparative-samplesolder material due to illumination of the light; and control means thatoutputs a deterioration parameter indicative of a comparativedeterioration degree of the test-sample solder material relative to thecomparative-sample solder material.

According to the above structure, the intensity detecting means detectsa first intensity at a particular wave number of infrared radiationreflected from the test-sample solder material due to illumination ofthe light, and a second intensity at the particular wave number ofinfrared radiation reflected from the comparative-sample solder materialdue to illumination of the light.

Here, the intensity at a particular wave number of infrared radiationreflected the solder material changes in accordance with the metaloxide, acid and salt contents in the solder material. This is becausethe metal oxide, acid and salt contained in the solder material has aproperty to absorb infrared radiation at a wave number specified.

Accordingly, if depending upon a first intensity at a particular wavenumber of infrared radiation reflected from the test-sample soldermaterial and a second intensity at the particular wave number ofinfrared radiation reflected from the comparative-sample soldermaterial, it is possible to determine a content of metal oxide, acid andsalt in the test-sample solder material relative to thecomparative-sample solder material. Here, the content is indicative of adeterioration degree (viscosity, oxidation degree and reducing power) ofthe solder material.

Therefore, in the above structure, the relative content is outputted asa deterioration parameter indicative of a comparative deteriorationdegree of the test-sample solder material relative to thecomparative-sample solder material. This allows the user of theapparatus to analyze the comparative content in the test-sample soldermaterial relative to the comparative-sample solder material by means ofdeterioration parameters outputted, and hence to test the comparativedeterioration degree in the test-sample solder material relative to thecomparative-sample solder material.

Meanwhile, the solder material test method of the inventionsatisfactorily analyzes at least one of metal oxide, acid and saltcontents. Accordingly, the particular wave number may be a wave numberincluded in a wave number band of infrared radiation to be absorbed bythe metal oxide included in the solder material. The metal oxide may be,for example, tin oxide or lead oxide.

Incidentally, the tin oxide and lead oxide has a property to absorb aninfrared ray at 520 cm⁻¹-700 cm⁻¹. Accordingly, the particular wavenumber is preferably a wave number included in a wave number band in arange of 520 cm⁻¹-700 cm⁻¹.

Meanwhile, the solder material test method of the inventionsatisfactorily analyzes at least one of metal oxide, acid and saltcontents. Accordingly, the particular wave number may be a wave numberincluded in an infrared radiation wave number band to be absorbed by theacid included in the solder material. The acid is preferably carboxylicacid. This is because, of the acids included in the solder material,carboxylic acid can be taken as an acid much in content.

Incidentally, carboxylic acid has a property to absorb infraredradiation at 1665 cm⁻¹-1730 cm⁻¹. Therefore, the particular wave numberis preferably included in a range of 1665 cm⁻¹-1730 cm⁻¹.

Furthermore, because the solder material test method is tosatisfactorily analyze at least one of metal oxide, acid and salt, theparticular wave number may be included in a wave number band whereinfrared radiation is absorbed by the salt contained in the soldermaterial. The salt is preferably carboxylate. This is because, of thesalts contained in the solder material, the salt much in content may becarboxylate.

Incidentally, carboxylate has a property to absorb infrared radiation at1270 cm⁻¹-1430 cm⁻¹. Therefore, the particular wave number is preferablyin a range of 1270 cm⁻¹-1430 cm⁻¹. Meanwhile, carboxylate has a propertyto absorb infrared radiation at 1500 cm⁻¹-1650 cm⁻¹. Therefore, theparticular wave number is preferably in a range of 1500 cm⁻¹-1650 cm⁻¹.

The test step may be a procedure to determine a difference between thefirst intensity and the second intensity. The deterioration parametermay be a difference between the first intensity and the secondintensity. The reason for this is as follows.

The difference is a parameter indicative of a difference degree in theinfrared absorbance at the particular wave number between thetest-sample solder material and the comparative-sample solder material.Namely, with such a difference, analysis can be made as to thedifference in the content of metal oxide, carboxylic acid andcarboxylate between the comparative sample solder material and thetest-sample solder material, making it possible to comparatively conducta test as to the viscosity, oxidation degree and reducing power of thetest-sample solder material relative to the comparative-sample soldermaterial, and hence as to the deterioration degree (viscosity, oxidationdegree and reducing power) of the test-sample solder material.

The test step may be a procedure to determine a ratio of the firstintensity and the second intensity. Furthermore, the deteriorationparameter may be a ratio of the first intensity and the secondintensity. The reason for this is as follows.

The difference is a parameter indicative of a difference degree in theinfrared absorbance at the particular wave number between thetest-sample solder material and the comparative-sample solder material.Namely, with such a difference, analysis can be made as to thedifference in the content of metal oxide, carboxylic acid andcarboxylate between the comparative sample solder material and thetest-sample solder material, making it possible to comparatively conducta test as to the viscosity, oxidation degree and reducing power of thetest-sample solder material relative to the comparative-sample soldermaterial, and hence as to the deterioration degree (viscosity, oxidationdegree and reducing power) of the test-sample solder material.

Incidentally, there may be a difference between the intensity ofinfrared radiation included in the light illuminated to the comparativesample and the intensity of infrared radiation included in the lightilluminated to the test sample. In this case, this difference isincluded in the difference between the first and second intensitiesdetected.

Preferably, a reference wave number is established that is a wave numberdifferent from the particular wave number, to detect further a thirdintensity of infrared radiation at the reference wave number reflectedfrom the test-sample solder material, and a fourth intensity of infraredradiation at the reference wave number reflected from thecomparative-sample solder material, thereby correcting at least any ofthe first and second intensities depending upon a difference between thethird and fourth intensities.

The test step may be a procedure to determine a first infrared radiationabsorbance at the particular wave number to the test-sample soldermaterial depending upon the first intensity, a second infrared radiationabsorbance at the particular wave number to the comparative-samplesolder material depending upon the first intensity, thereby determininga difference between the first infrared radiation absorbance and thesecond infrared radiation absorbance. Furthermore, the control means maydetermine a first infrared radiation absorbance at the particular wavenumber to the test-sample solder material depending upon the firstintensity, a second infrared radiation absorbance at the particular wavenumber to the comparative-sample solder material depending upon thefirst intensity, thereby outputting, as a deterioration parameter, adifference between the first infrared radiation absorbance and thesecond infrared radiation absorbance. The reason for this is as follows.

The difference between the first and second infrared radiationabsorbances is a parameter indicative of a difference degree in theinfrared radiation absorbance at the particular wave number between thetest-material solder material and the comparative-sample test material.Accordingly, with such a difference, analysis can be made as to thedifference in the content of metal oxide, carboxylic acid andcarboxylate between the comparative sample solder material and thetest-sample solder material, making it possible to comparatively conducta test as to the viscosity, oxidation degree and reducing power of thetest-sample solder material relative to the comparative-sample soldermaterial, and hence as to the deterioration degree (viscosity, oxidationdegree and reducing power) of the test-sample solder material.

The test step may be a procedure to determine a first infrared radiationabsorbance at the particular wave number to the test-sample soldermaterial depending upon the first intensity, a second infrared radiationabsorbance at the particular wave number to the comparative-samplesolder material depending upon the first intensity, thereby determininga ratio of the first infrared radiation absorbance and the secondinfrared radiation absorbance. Furthermore, the control means mayperform a processing to determine a first infrared radiation absorbanceat the particular wave number to the test-sample solder materialdepending upon the first intensity, a second infrared radiationabsorbance at the particular wave number to the comparative-samplesolder material depending upon the first intensity, thereby outputting,as a deterioration parameter, a ratio of the first infrared radiationabsorbance and the second infrared radiation absorbance. The reason forthis is as follows.

The ratio of the first infrared radiation absorbance and the secondinfrared radiation absorbance is a parameter indicative of a differencedegree in the infrared radiation absorbance at the particular wavenumber between the test-material solder material and thecomparative-sample test material. Accordingly, with such a ratio,analysis can be made as to the difference in the content of metal oxide,carboxylic acid and carboxylate between the comparative sample soldermaterial and the test-sample solder material, making it possible tocomparatively conduct a test as to the viscosity, oxidation degree andreducing power of the test-sample solder material relative to thecomparative-sample solder material, and hence as to the deteriorationdegree (viscosity, oxidation degree and reducing power) of thetest-sample solder material.

There may be a difference between the intensity of infrared radiationincluded in the light illuminated to the comparative sample and theintensity of infrared radiation included in the light illuminated to thetest sample. In this case, this difference is included in the differencebetween the first and second intensities detected, and hence in thedifference between the first and second infrared radiation absorbances.

Accordingly, a reference wave number is satisfactorily establisheddifferent in wave number from the particular wave number, to detectfurther a third intensity at the reference wave number of infraredradiation reflected from the test-sample solder material, and a fourthintensity at the reference wave number of infrared radiation reflectedfrom the comparative-sample solder material. Furthermore, it ispreferred to determine a third infrared radiation absorbance at thereference wave number to the test-sample solder material depending uponthe third intensity, and a fourth infrared radiation absorbance at thereference wave number to the test-sample solder material depending uponthe fourth intensity, thereby correcting at least any of the first andsecond infrared radiation absorbances depending upon a differencebetween the third infrared radiation absorbance and the fourth infraredradiation absorbance.

The control means may be realized by a computer. In this case, a controlprogram for realizing the control means on the computer and acomputer-readable recording medium recording the control program arewithin the scope of the invention.

As described so far, a solder material test method in the inventionincludes: a first detecting step of detecting a first intensity at aparticular wave number of infrared radiation reflected from atest-sample solder material by illuminating light to the test-samplesolder material; a second detecting step of detecting a second intensityat the particular wave number of infrared radiation reflected from acomparative-sample solder material by illuminating light to thecomparative-sample solder material; and a test step of testing adeterioration degree of the test-sample solder material relative to thecomparative-sample solder material, depending upon the first and secondintensities detected.

Therefore, the metal oxide, acid and salt contents in a test-samplesolder material can be analyzed relative to a comparative-sample soldermaterial. This makes it possible to test the test-sample solder materialfor viscosity, oxidation degree and reducing power. Hence, thetest-sample solder material can be tested for deterioration degree(viscosity, oxidation degree and reducing power) relative to thecomparative-sample solder material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a spectrum chart, showing an infrared radiation absorbance ofa test-sample solder material and an infrared radiation absorbance of acomparative-sample solder material, obtained by a solder material testmethod in an example of the invention;

FIG. 2 is a table showing ingredients and a composition (by weight %) ofa test-sample solder material in the solder material test method in anexample of the invention;

FIG. 3 is a chart showing an absorbance difference obtained bysubtracting an infrared radiation absorbance of comparative-samplesolder material from an infrared radiation absorbance of test-samplesolder material;

FIG. 4A is a chart showing, for each test sample, the absorbancedifferences, as to a plurality of test samples, obtained by subtractinginfrared radiation absorbance of comparative-sample solder material froman infrared radiation absorbance of test-sample solder material whileFIG. 4B is a table showing the number of print cycles, viscosity andinfrared radiation absorbance at predetermined wave number of aplurality of test samples;

FIG. 5 is a chart showing, for each test sample, the absorbancedifferences, as to a plurality of test samples, obtained by subtractinginfrared radiation absorbance to comparative-sample solder material frominfrared radiation absorbance to test-sample solder material, in awave-number band of 520 cm⁻¹-700 cm⁻¹;

FIG. 6 is a chart showing, for each test sample, the absorbancedifferences, as to a plurality of test samples, obtained by subtractinginfrared radiation absorbance to comparative-sample solder material frominfrared radiation absorbance to test-sample solder material, in awave-number band of 1270 cm⁻¹-1420 cm⁻¹;

FIG. 7 is a chart showing, for each test sample, the absorbancedifferences, as to a plurality of test samples, obtained by subtractinginfrared radiation absorbance to comparative-sample solder material frominfrared radiation absorbance to test-sample solder material, in awave-number band of 1500 cm⁻¹-1650 cm⁻¹;

FIG. 8 is a chart showing, for each test sample, the absorbancedifferences, as to a plurality of test samples, obtained by subtractinginfrared radiation absorbance to comparative-sample solder material frominfrared radiation absorbance to test-sample solder material, in awave-number band of 1665 cm⁻¹-1725 cm⁻¹;

FIG. 9 is a typical view showing a solder material test apparatus thatrealizes the solder material test method in the example of theinvention;

FIG. 10 is a typical view showing a modification to the solder materialtest apparatus shown in FIG. 9;

FIG. 11 is a typical view showing another modification to the soldermaterial test apparatus shown in FIG. 9;

FIG. 12 is a typical view showing further modification to the soldermaterial test apparatus shown in FIG. 9;

FIG. 13 is a typical view showing an arrangement further modified thesolder material test apparatus shown in FIG. 12;

FIG. 14 is a typical view showing an arrangement modified, forin-line-analysis use, the solder material test apparatus shown in FIG.12;

FIG. 15 is a typical view showing an arrangement modified the soldermaterial test apparatus shown in FIG. 14; and

FIG. 16 is a typical view showing a solder material test apparatus in afurther different form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Solder Material Test Method

A solder material test method in this embodiment uses infraredradiation, to test a solder material for deterioration degree by usinginfrared radiation. Note that “solder material” in the embodimentsignifies a creamy solder paste for use on a production line for aprinted board. In the invention, however, it is not limited to such asolder paste but is applicable generally to the solder materials wellknown.

Now the solder material test method in the embodiment is detailed in thebelow.

When a solder material is continuously used or exposed to the externalair, the metal in the solder oxidizes and the carboxylic acid thereinturns into carboxylate. Namely, when a solder material is used orcontinuously exposed to the external air, the metal oxide containedincreases, the carboxylic acid contained decreases and the carboxylatecontained increases in the solder material.

There arises a phenomenon that the solder material is increased inoxidation degree by the increase of metal oxide, increased in viscosityby the increase of carboxylic acid and decreased in reduction power bythe content decrease of carboxylic acid. The phenomenon is calleddeterioration of a solder.

Accordingly, in case a test-sample solder material can be analyzed forat least one of metal oxide content, carboxylic acid content andcarboxylate content, the solder material can be tested for at least oneof viscosity, oxidation degree and reduction power, and ultimately fordeterioration degree.

Meanwhile, it is known that each of metal oxide, carboxylic acid andcarboxylate is to absorb infrared radiation at a particular wave-numberband specified for same.

Accordingly, a solder material test method in this embodiment isrealized by implementing a combination of the following steps. At first,a first detecting step is performed to detect a first intensity at aparticular wave number of infrared radiation reflected from atest-sample solder material by illuminating light to the test-samplesolder material. Then, a second detecting step is performed to detect asecond intensity at the particular wave number of infrared radiationreflected from a comparative-sample solder material by illuminatinglight to the comparative-sample solder material. Based on theintensities thus detected, a test step is performed to test adeterioration degree of the test-sample solder material relatively to adeterioration degree of the comparative-sample solder material.Incidentally, the first and second detecting steps may be reverse orsimultaneous in the order.

According to the solder material test method in the present embodiment,the first and second detecting steps are to detect a first intensity ata particular wave number of infrared radiation reflected from thetest-sample solder material and a second intensity at a particular wavenumber of infrared radiation reflected from the comparative-samplesolder material.

Here, metal oxide, carboxylic acid and carboxylate are each to absorbinfrared radiation at a particular wave number band specified thereon.Accordingly, in accordance with the content of metal oxide, carboxylicacid and carboxylate in a solder material, the solder material ischanged in the absorbing amount of infrared radiation at a particularwave number. This changes the intensity at a particular wave number ofinfrared radiation reflected the solder material.

Accordingly, if based on the intensities detected in the first andsecond detecting steps, it is possible to determine at least one ofmetal oxide, acid and salt contents in the test-sample solder materialrelatively to the comparative-sample solder material. Therefore, thetest-sample solder material can be tested for deterioration degreerelatively to the comparative-sample solder material.

Incidentally, the test step may be in the form of (a) a procedure todetermine a difference between the first intensity and the secondintensity, (b) a procedure to determine a ratio of the first intensityand the second intensity, (c) a procedure to determine a first infraredradiation absorbance at the particular wave number to test-sample soldermaterial from the first intensity and a second infrared radiationabsorbance at the particular wave number to comparative-sample soldermaterial from the second intensity, thereby determining a differencebetween the first and second infrared radiation absorbances, and (d) aprocedure to determine a ratio of the first infrared radiationabsorbance and the second infrared radiation absorbance.

The difference and the ratio are parameters each indicative of adifference degree in the infrared radiation absorbance at the particularwave number between the comparative-sample solder material and thetest-sample solder material. By determining these parameters, it ispossible to analyze the difference in the content of metal oxide,carboxylic acid and carboxylate between the comparative-sample soldermaterial and comparative-sample solder material. This makes it possibleto test the test-sample solder material for viscosity, oxidation degreeand reducing power relatively to the comparative-sample solder material,and hence to test the test-sample solder material for deteriorationdegree (viscosity, oxidation degree and reducing power) relatively.

Incidentally, in the test step, in case the practicer for the soldermaterial test method merely compares between the detected intensitieswithout determining the difference or ratio, the test-sample soldermaterial can be determined for deterioration degree relatively to thecomparative-sample solder material.

Meanwhile, the test and comparative samples may use different soldermaterials or the same solder material.

Incidentally, the “use the same solder material” refers to such a casethat, say, a solder material “a” in a new-product state is taken as acomparative sample while the solder material “a” in a post-use state(after a use in a board-print process) is taken as a test sample.Otherwise, a solder material “b”, printed the number of print cycles 100in a board-print process, may be taken as a comparative sample while therelevant solder material “b”, printed the number of print cycles 200 betaken as a test sample.

EXAMPLE 1

Now described is an example of the solder material test method in thisembodiment shown in the above.

A solder material to be tested is first described in this example. Thisexample used, in the test, a solder material containing the ingredientsshown in FIG. 2. As shown in the figure, the solder material in thisexample contains 80-90 percent of tin, 1-3 percent of silver, less than1 percent of copper, 2-4 percent of diethylene glycol monohexyl ether,less than 1 percent of 2-ethyl-1,3-hexanediol and 4-6 percent of rosin.

Incidentally, although the solder material has the main ingredient of ametal, such as tin (Sn) or lead (Pb), the solder material in the exampleuses tin as such a metal, as shown in FIG. 2. Meanwhile, the soldermaterial in this example employs rosin (C₁₉H₂₉COOH) as carboxylic acid,a main ingredient providing reducing power to the solder material, asshown in FIG. 2.

This example employed, as a comparative sample, a solder material havinga composition shown in FIG. 2 and in a new-product state, and as a testsample a solder material used in a print process for a printed board.Incidentally, from now on, the comparative-sample solder material may bereferred merely to as “comparative sample” while the test-sample soldermaterial as “test sample”.

Here, infrared radiation illumination was conducted at equal intensitiesrespectively to the comparative and test samples, to detect theintensity (second intensity) of infrared radiation reflected thecomparative sample at a band of 500 cm⁻¹-3000 cm⁻¹ and the intensity(first intensity) of infrared radiation reflected the test sample at aband of 500 cm⁻¹-3000 cm⁻¹ (first detection step, second detectionstep).

Furthermore, this example calculated, for each wave number, anabsorbance of infrared radiation to the comparative sample (secondinfrared radiation absorbance) and an absorbance of infrared radiationto the test sample (first infrared radiation absorbance). Incidentally,the absorbance can be determined by operating, for each wave number,an infrared radiation absorbance to the comparative sample(absorbancecorresponding to wave number h)A′=−log(A/BL)  (1) andan infrared radiation absorbance to the test sample (absorbancecorresponding to wave number h)B′=−log(B/BL)  (2),on the assumption that the Planck value corresponding to wave number h(intensity at wave number h of the infrared radiation illuminated) isBL, the intensity at wave number h of the infrared radiation reflectedfrom the comparative sample is A and the intensity at wave number h ofthe infrared radiation reflected from the test sample is B.

FIG. 1 is a spectrum chart showing an absorbance calculated. In thefigure, the abscissa represents a wave number of infrared radiationwhile the coordinate an absorbance of infrared radiation.

As shown in the figure, observed is a difference between the absorbanceof infrared radiation to the comparative sample and the absorbance ofinfrared radiation to the test sample.

Then, considerations were made on the difference. Specifically,differences were operated as to A′ and B′ corresponding respectively tothe wave numbers determined by (1) and (2), according to equation (11).The difference, hereinafter is referred to as “absorbance difference”.Absorbance difference=B′−A′  (11)Namely, the absorbance difference referred here is obtained bysubtracting the infrared radiation absorbance of the comparative samplefrom the infrared radiation absorbance of the test sample, which isindicative of a difference between the infrared radiation absorbance ofthe test sample and the infrared radiation absorbance of the comparativesample.

FIG. 3 is a chart showing a relationship between a wave number ofinfrared radiation and an absorbance difference corresponding to thewave number. Namely, the FIG. 3 chart shows an absorbance differencethat is a subtraction of an absorbance of the comparative sample from anabsorbance of the test sample.

From FIG. 3, it can be known that there is a great difference betweenthe comparative sample and the test sample, with respect to theabsorbance at around 600 cm⁻¹, 1300 cm⁻¹, 1600 cm⁻¹ and 1700 cm⁻¹.

Specifically, it can be known that the infrared radiation absorbance ofthe test sample is higher than the infrared radiation absorbance of thecomparative sample, at around 600 cm⁻¹, 1300 cm⁻¹ and 1600 cm⁻¹. It canbe also known that the infrared radiation absorbance of the test sampleis lower than the infrared radiation absorbance of the comparativesample, at around 1700 cm⁻¹.

It is known that, on the infrared radiation spectrum chart, theabsorption observed at around 600 cm⁻¹ is due to the vibration based onan oxygen-metal bond of a metal oxide. The absorption observed at around1300 cm⁻¹ is known to be due to the symmetric stretching vibration basedon carboxylic acid while the absorption observed at around 1600 cm⁻¹ isknown due to the asymmetric stretching vibration based on carboxylate.Furthermore, the absorption observed at around 1700 cm⁻¹ is known toshow an absorption due to the stretching vibration based on double-bondin carboxylic acid.

From the fact that the infrared radiation absorbance at around 600 cm⁻¹is higher for the test sample than for the comparative sample, it can beunderstood that the test sample contains metal oxide in a greater amountand higher in oxidation degree than the comparative sample.

Moreover, from the fact that the infrared radiation absorbance at around1300 cm⁻¹ and 1600 cm⁻¹ is higher for the test sample than for thecomparative sample, it can be understood that the test sample containscarboxylate greater in amount and higher in viscosity than thecomparative sample.

Furthermore, from the fact that the infrared radiation absorbance ataround 1700 cm⁻¹ is lower for the test sample than for the comparativesample, it can be understood that the test sample contains a loweramount of carboxylic acid less and is lower in reducing power than thecomparative sample.

In this manner, this example determines, for each wave number of theinfrared radiation spectrum, an infrared radiation absorbance for thetest-sample cream solder (first infrared radiation absorbance) and aninfrared radiation absorbance for the comparative-sample cream solder(second infrared radiation absorbance), respectively from an intensityof an infrared radiation reflected from the test-sample cream solder(intensity from test sample) and an intensity of an infrared radiationreflected from the comparative-sample cream solder (intensity fromcomparative sample).

Then, for each wave number of infrared radiation spectrum, an absorbancedifference is determined that is a subtraction of an absorbance of thecomparative-sample cream solder from an absorbance of the test-samplecream solder. By referring to the absorbance difference of at around 600cm⁻¹, 1300 cm⁻¹, 1600 cm⁻¹ and 1700 cm⁻¹, it is possible to determinecomparatively the content of metal oxide, carboxylic and carboxylate inthe test-sample cream solder relative to that in the comparative-samplecream solder.

From the metal oxide content, it is possible to determine comparativelythe oxidation degree of the test-sample cream solder. From thecarboxylic-acid content, it is possible to determine comparatively thereducing power of the test-sample cream solder. From the carboxylatecontent, it is possible to determine comparatively the viscosity of thetest-sample cream solder.

FIG. 4A shows a result of an analysis conducted on a cream solder takenin a new-product state as a comparative sample and cream solders,printed in the number of cycles of 200, 400, 600, 800, 1000 and 1200times, respectively, through the printing process to the boards, as testsamples, according to the method shown in the present example.

FIG. 4A is a chart showing, for each test sample, a relationship betweenan infrared radiation wave number and an absorbance difference obtainedby subtracting an absorbance of the comparative-sample cream solder froman absorbance of a test-sample cream solder corresponding to the wavenumber. The abscissa represents an infrared radiation wave number whilethe ordinate represents an absorbance difference that is a difference inabsorbance between the comparative-sample cream solder and thetest-sample cream solder.

From FIG. 4A, it can be seen that the absorbance increases at around1300 cm⁻¹ and 1600 cm⁻¹ with the increasing number of print cycles ofcream solder whereas the absorbance is decreased at around 1700 cm⁻¹.From this fact, it can be understood that, in the cream solder, thecarboxylic acid decreases and the carboxylate increases with theincreasing number of print cycles. From the result of increasingcarboxylic acid, it can be analyzed that the viscosity of the creamsolder increases with the increasing number of print cycles.

When the test samples are actually measured for viscosity, it wasconfirmed that there is a positive correlation between the number ofprint cycles with cream solder and the viscosity of cream solder asshown in FIG. 4B. It was also confirmed that there is a positivecorrelation between the infrared radiation absorbance of the creamsolder at around 1600 cm⁻¹ and the viscosity of the cream solder whereasthere is a negative correlation between the infrared radiationabsorbance of the cream solder at around 1700 cm⁻¹ and the viscosity ofthe cream solder. The reason why such relationships are held is becauseof the following. Namely, as the number of cream-solder-print cyclesincreases, the carboxylic acid contained in the cream solder decreasesto decrease the infrared radiation absorbance at around 1700 cm⁻¹whereas the carboxylate contained in the cream solder increases toincrease the infrared radiation absorbance at around 1600 cm⁻¹, whereinthe viscosity increases with increasing carboxylate.

The embodiment shown in the above calculated the infrared radiationabsorbance of the test-sample cream solder and the infrared radiationabsorbance of the comparative-sample cream solder. However, unlesscalculating an absorbance, it is possible to determine comparatively thecontent of metal oxide, carboxylic and carboxylate in the test-samplecream solder. Specifically, for each wave number of 500 cm⁻¹-3000 cm⁻¹,detected are the intensity of infrared radiation reflected thetest-sample cream solder and the intensity of an infrared radiationreflected the comparative-sample cream solder. For each wave number,operation is made on each intensity detected, according to equation(21).Intensity difference=B−A  (21)

A: intensity of an infrared radiation reflecting from the comparativesample.

B: intensity of an infrared radiation reflecting from the test sample.

Here, “intensity difference” is a subtraction of the infrared radiationintensity detected of the comparative sample from the infrared radiationintensity detected of the test sample, i.e. a difference between theinfrared radiation intensity detected of the test sample and theinfrared radiation intensity detected of the comparative sample.

By referring to the absorbance difference at 600 cm⁻¹, 1300 cm⁻¹, 1600cm⁻¹ and 1700 cm⁻¹, it is possible to determine the difference ininfrared radiation absorption based on the metal oxide, carboxylic andcarboxylate of the test-sample cream solder, relative to thecomparative-sample cream solder. For this reason, it is possible todetermine the content of metal oxide, carboxylic and carboxylate in thetest-sample cream solder, relative to the comparative-sample creamsolder.

Meanwhile, by using a ratio in absorbance or in intensity instead of theabsorbance or intensity difference, it is possible to determine thedifference in infrared radiation absorbance between the comparative andtest samples, and hence to comparatively determine the content of metaloxide, carboxylic and carboxylate in the test-sample cream solder.

For example, for each wave number, the intensity ratio may be determinedthat is a ratio of the infrared radiation intensity detected of the testsample and the infrared radiation intensity detected of the comparativesample, according to the following operation.Intensity ratio=B/A  (31)

For each wave number, the absorbance ratio may be determined that is aratio of an infrared radiation absorbance of the test sample and aninfrared radiation absorbance of the comparative sample, according tothe following operation.Absorbance ratio=B′/A′  (41)

A′: infrared radiation absorbance of the comparative sample.

B′: infrared radiation absorbance of the test sample. According to theexamples shown above, infrared radiation intensity detection is requiredfor each wave number of 5000-3000 cm⁻¹ for the cream solders of thecomparative and test samples, to calculate an infrared radiationabsorbance difference, absorbance ratio, intensity difference orintensity ratio. Alternatively, the procedure may be taken to detect theintensity only at a particular wave number of infrared radiation, tocalculate an absorbance, absorbance difference, intensity ratio,intensity difference or intensity ratio as to the particular wavenumber. The particular wave number means a wave number where infraredradiation absorption is recognized based on at least one of metal oxide,carboxylic acid and carboxylate. In this example, it is at least one of600 cm⁻¹, 1300 cm⁻¹, 1600 cm⁻¹ and 1700 cm⁻¹.

Meanwhile, the light illuminated from the floodlight 15 is non-uniformin intensity. Even where an infrared radiation is illuminated to thecomparative and test samples by using the same floodlight 15, ifinfrared radiation illumination is different in timing, there occurs asa slight difference between the intensity of infrared radiationilluminated to the comparative sample and the intensity of infraredradiation illuminated to the test sample. Such a difference may have abad effect upon the intensity of infrared radiation reflecting from thecream solder.

For this reason, correction is preferably made in determining anintensity difference, intensity ratio, absorbance difference orabsorbance ratio at a particular wave number. Below, explanation is madeon a procedure to determine a corrected one of intensity difference,intensity ratio, absorbance difference or absorbance ratio.

At first, a solder-material test apparatus 1 is set with a referencewave number outside the wave number band, where infrared radiationabsorption based on a metal oxide, carboxylic acid and carboxylate isobserved, at which wave number there is no difference in reflectedinfrared radiation intensity between the comparative and test samples.

Then, detected are the intensity at the reference wave number ofinfrared radiation reflected from comparative sample and the intensityat the reference wave number of infrared radiation reflected from thetest sample. Furthermore, detected are an intensity at the particularwave number of infrared radiation reflected upon the comparative sampleand the intensity at the particular wave number of infrared radiationreflected from the test sample.

Here, it is assumed that the intensity at the reference wave number ofinfrared radiation reflected from the comparative sample(comparative-sample reference intensity) is A_(ref), the intensity atthe reference wave number of infrared radiation reflected from the testsample (test-sample reference intensity) is B_(ref), the intensity atthe particular wave number of infrared radiation reflected from thecomparative sample (comparative-sample intensity) is A_(tar) and theintensity at the particular wave number of infrared radiation reflectedfrom the test sample (test-sample intensity) is B_(tar).

Meanwhile, it is assumed that the infrared radiation absorbance at thereference wave number of the comparative sample (fourth infraredradiation absorbance) is A′_(ref), the infrared radiation absorbance atthe reference wave number of the test sample (third infrared radiationabsorbance) is B′_(ref), the infrared radiation absorbance at theparticular wave number to comparative sample (second infrared radiationabsorbance) is A′_(tar) and the infrared radiation absorbance at theparticular wave number of the test sample (first infrared radiationabsorbance) is B′_(tar).

The absorbances are calculated according to the similar technique toequations (1), (2). Namely, it can be determined by the followingprovided that the intensity corresponding to a reference wave number ofinfrared radiation to be illuminated to the comparative sample isBL_(ref) and the intensity corresponding to a particular wave number ofinfrared radiation to be illuminated to the test sample is BL_(tar).A′ _(ref)=−log(A _(ref) /BL _(ref))  (61)B′ _(ref)=−log(B _(ref) /BL _(ref))  (62)A′ _(tar)=−log(A _(tar) /BL _(tar))  (63)B′ _(tar)=−log(B _(tar) /BL _(tar))  (64)

Then, corrected intensity difference, corrected intensity ratio,corrected absorbance difference and corrected absorbance ratio can bedetermined by the following.Corrected intensity difference=(B _(tar) −B _(ref))−(A _(tar) −A_(ref))  (71)Corrected intensity ratio=(B _(tar) −B _(ref))/(A _(tar) −A_(ref))  (72)Corrected absorbance difference=(B′ _(tar) −B′ _(ref))−(A′ _(tar) −A′_(ref))  (73)Corrected absorbance difference=(B′ _(tar) −B′ _(ref))/(A′ _(tar) −A′_(ref))  (74)

Due to this, even when there is a slight difference between theintensity of infrared radiation to be illuminated to the comparativesample and the intensity of infrared radiation to be illuminated to thetest sample, it is possible to determine a corrected intensitydifference, corrected intensity ratio, corrected absorbance differenceand corrected absorbance ratio with such a difference nearly eliminatedbecause the intensities and absorbance are each subtracted by anintensity at the reference wave number corresponding to the difference.

Corrected intensity difference, corrected intensity ratio, correctedabsorbance difference and corrected absorbance ratio can be determinedby the following.Corrected intensity difference=(B _(tar) ×A _(ref) /B _(ref))−A_(tar)  (75)Corrected intensity ratio=(B _(tar) ×A _(ref) /B _(ref))/A _(tar)  (76)Corrected absorbance difference=(B′ _(tar) ×A′ _(ref) /B′ _(ref))−A′_(tar)  (77)Corrected absorbance ratio=(B′ _(tar) ×A′ _(ref) /B′ _(ref))/A′_(tar)  (78)This method uses A_(ref)/B_(ref) or A′_(ref)/B′_(ref) as a correctioncoefficient for the difference.

Meanwhile, the particular wave numbers (600 cm⁻¹, 1300 cm⁻¹, 1600 cm⁻¹,1700 cm⁻¹) can be changed in value. Namely, the particular wave numbersare not limited to 600 cm⁻¹, 1300 cm⁻¹, 1600 cm⁻¹, 1700 cm⁻¹, buteffective ranges can be established for particular wave numbers. Thispoint is detailed.

At first, by taking a solder material in a new product state as acomparative sample and solder materials printed the number of cycles of200, 400, 600, 800, 1000 and 1200 through the printing process as testsamples, the absorbance differences were determined for the test samplesaccording to the method shown in the example. The result is shown inFIGS. 5 to 8. FIG. 5 shows the absorbance differences at a wave numberband of 520 cm⁻¹-700 cm⁻¹, FIG. 6 the absorbance differences at a wavenumber band of 1270 cm⁻¹-1430 cm⁻¹, FIG. 7 the absorbance differences ata wave number band of 1500 cm⁻¹-1650 cm⁻¹, and FIG. 8 the absorbancedifferences at a wave number band of 1665 cm⁻¹-1730 cm⁻¹.

The metal oxide (tin dioxide) contained in the solder material has anabsorption peak to be detected at around 600 cm⁻¹. However, as shown inFIG. 5, if detecting at 520 cm⁻¹-700 cm⁻¹, the absorption differencescan be distinguished in differences between the test samples. Ifdetecting at 557-613 cm⁻¹, the absorption differences can be observedmore conspicuously in difference between the test samples. Consequently,by taking at least any one of wave numbers lying between 520 cm⁻¹-700cm⁻¹ as a particular wave number, metal oxide content can be analyzed onthe test sample.

Meanwhile, the symmetric stretching vibration based on carboxylic acidhas an absorption peak to be detected at around 1300 cm⁻¹ (exactly 1323cm⁻¹). However, as shown in FIG. 6, If detecting at 1270 cm⁻¹-1430 cm⁻¹,the absorption differences can be distinguished in difference betweenthe test samples. If detecting at 1282 cm⁻¹-1382 cm⁻¹, the absorptiondifferences can be observed more conspicuously in difference between thetest samples. Consequently, by taking at least any one of wave numberslying between 1270 cm⁻¹-1430 cm⁻¹ as a detected wave number, carboxylatecontent can be analyzed as to the sample.

The assymetric stretching vibration based on carboxylate has anabsorption peak to be detected at around 1600 cm⁻¹ (exactly 1590 cm⁻¹).However, as shown in FIG. 7, If detecting at 1500 cm⁻¹-1650 cm⁻¹, theabsorption differences can be distinguished in difference between thetest samples. If detecting at 1562 cm⁻¹-1624 cm⁻¹, the absorptiondifferences can be observed more conspicuously in differences betweenthe test samples. Consequently, by taking at least any one of wavenumbers lying between 1500 cm⁻¹-1650 cm⁻¹ as a wave number fordetection, carboxylate content can be analyzed on the test sample.

Furthermore, the carbon-oxygen double bond of carboxylate has anabsorption peak to be detected at around 1700 cm⁻¹ (exactly 1590 cm⁻¹).However, as shown in FIG. 8, If detecting at 1665 cm⁻¹-1730 cm⁻¹, theabsorption differences can be distinguished in differences between thetest samples. If detecting at 1683 cm⁻¹-1710 cm⁻¹, the absorptiondifferences can be observed more conspicuously in differences betweenthe test samples. Consequently, by taking at least any one of wavenumbers lying between 1665 cm⁻¹-1730 cm⁻¹ as a wave number fordetection, carboxylic acid content can be analyzed on the test sample.

Solder Material Test Apparatus

Now described is a solder material test apparatus that realizes thesolder material test method in the embodiment. Note that the soldermaterial test apparatus, described below, is a mere exemplification ofthe apparatus that realizes the solder material test method in theembodiment, i.e. the solder material test apparatus described below isnot necessarily needed in realizing the solder material test method inthe embodiment.

The solder material test apparatus in this embodiment includes a lightsource that illuminates light to the test-sample and comparative-samplesolder materials, intensity detecting means that detects a firstintensity at a particular wave number of infrared radiation reflectedfrom the test-sample solder material due to the light illumination and asecond intensity at the particular wave number of infrared radiationreflected from the comparative-sample solder material due to the lightillumination, and control means that outputs a deterioration parameterindicative of a comparative deterioration degree of the test-samplesolder material relative to the comparative-sample solder material.

Here, the deterioration parameter includes a difference between thefirst intensity and the second intensity and a ratio of the firstintensity and the second intensity. Alternatively, by determining, fromthe first intensity, a first infrared radiation absorbance at theparticular wave number of the test-sample solder material and, from thefirst intensity, a second infrared radiation absorbance at theparticular wave number of the comparative-sample solder material, thedeterioration parameter may be provided as a difference between thefirst and second infrared radiation absorbances thus obtained.Furthermore, the deterioration parameter may be by the ratio of thefirst infrared radiation absorbance and the second infrared radiationabsorbance.

Due to this, the deterioration parameter is given indicative of adifference degree between the infrared radiation absorbance at aparticular wave number of the test-sample solder material and theinfrared radiation absorbance at a particular wave number of thecomparative-sample solder material. Here, depending upon the content ofmetal oxide, carboxylic acid and carboxylate in the solder material, theinfrared radiation absorbance at a particular wave number of soldermaterial changes to change the intensity of an infrared radiation at theparticular wave number reflected from the solder material.

Accordingly, by referring to the deterioration parameter, the operatorat the solder material test apparatus is allowed to know the content ofmetal oxide, carboxylic acid and carboxylate in the test-sample soldermaterial. Thus, he/she can conduct a test on a test-sample soldermaterial for relative deterioration degree.

In case an infrared radiation-transmissive optical filter is providedbetween the light source and the solder material or between the soldermaterial and the intensity detecting means in the above arrangement, theintensity detecting means is allowed to detect infrared radiationreflected from the solder material.

Now description is made on an example of the solder material testapparatus in the present embodiment.

EXAMPLE 2

A solder material test apparatus 100 in this example has a light source10, a band-pass filter 11, a plate 12, a solder material 13, aphotoelectric converter (intensity detecting means) 14, a controlsection (control means) 15 and a display section (display means) 16, asshown in FIG. 9.

The light source 10 is a lamp that illuminates light toward the plate12, which employs, say, a ceramic light source.

The band-pass filter 11 is an optical filter arranged on the opticalaxis of the light source 10, at between the light source 10 and theplate 12. The band-pass filter 11 transmits an infrared radiation at aparticular wave number only. The particular wave number is similar tothe explanation in example 1, at which wave number infrared radiationabsorption is recognized due to at least one of metal oxide, carboxylicacid and carboxylate.

The plate 12 is a stage on which a solder material 13 is to be placed.The light from the light source 10 is illuminated to the solder material13 rested on the plate 12 through the band-pass filter 11. Accordingly,the light illuminated to the solder material 13 is of infrared radiationat a particular wave number.

The solder material 13 is relevant to the foregoing comparative-sampleor test-sample solder material, which is reflective of the lightilluminated.

The photoelectric converter 14 is to detect the intensity of incominginfrared radiation. The photoelectric converter 14 generates an analogsignal indicative of the detected intensity of infrared radiation andforwards the analog signal to the control section 15. The photoelectricconverter 14 is, for example, a device using MCT (photoconductor,HgCdTe). The photoelectric converter 14 is arranged in a position axialof infrared radiation reflected from the solder material 13 on the plate12.

The control section 15 is a block for processing the analog signal sentfrom the photoelectric converter 14, which is configured with an A/D(analog to digital) converter that converts an analog signal into adigital signal, and a computer that performs a data processing dependingupon the digital signal.

The display section 16 is a display panel that displays an image basedon the image data sent from the control section 15.

According to the solder material test apparatus 100, the digital signalprocessed by the computer of the control section 15 provides dataindicative of the intensity at a chosen wave number of the infraredradiation reflected from the solder material 13.

In the solder material test apparatus 100, a comparative-sample soldermaterial 13 is placed on the plate 12. By illuminating infraredradiation at a particular wave number to the solder material 13, thephotoelectric converter 14 is caused to detect the intensity of infraredradiation (second intensity) reflected from the comparative-samplesolder material 13. Thereafter, a test-sample solder material 13 is puton the plate 12, to detect the intensity of infrared radiation (firstintensity) by a similar operation. Due to this, the control section 15is delivered with the data indicative of the intensity of infraredradiation reflected the comparative-sample solder material 13 and thedata indicative of the intensity of infrared radiation reflected thetest-sample solder material 13, in order.

Depending upon the intensities, the control section 15 determinesinfrared radiation absorbance at a particular wave number of the testsample (first infrared radiation absorbance) and infrared radiationabsorbance at a particular wave number of the comparative sample (secondinfrared radiation absorbance). The control section 15 furtherdetermines an absorbance difference, a subtraction of the infraredradiation absorbance at a wave number considered of the test sample fromthe infrared radiation absorbance at a wave number considered of thecomparative sample. The display section 16 is caused to display an imagerepresentative of the absorbance difference. This allows the operator atthe solder material test apparatus 100 to analyze the test sample for atleast one of metal-oxide relative content, carboxylic acid relativecontent and carboxylate relative content, and hence the relativedeterioration degree of the test-sample solder material.

Alternatively, the control section 15 may be configured to output any of(a) an absorbance ratio that is a ratio of an infrared radiationabsorbance at a particular wave number of the sample and an infraredradiation absorbance at a particular wave number of the comparativesample, (b) an intensity difference that is a subtraction of anintensity of infrared radiation at a particular wave number reflectedfrom the test sample from an intensity of infrared radiation at aparticular wave number reflected from the comparative sample, and (c) anintensity ratio that is a ratio of an intensity of infrared radiation ata particular wave number reflected from the test sample to an intensityof infrared radiation at a particular wave number reflected from thecomparative sample. Namely, it may be configured to operate any one ofequations (21), (31) and (41) and output the result thereof.

In the solder material test apparatus 100, the control section 15 may beconnected with a storage section 20, as shown in FIG. 10. Thisarrangement can previously detect only the intensity of infraredradiation reflected the comparative-sample solder material and storedata indicative of the intensity in the storage section 20. Thissatisfactorily requires to once detect the intensity of infraredradiation reflected from the comparative-sample solder material evenwhere tests must be made successively on a plurality of test samples.

Instead of the arrangement of the band-pass filter 11 between the lightsource 10 and the plate 12, the band-pass filter 11 may be provided,between the solder material 13 on the plate 12 and the photoelectricconverter 14, on the optical axis of the light reflected from the soldermaterial 13, as shown in FIG. 11.

As shown in FIG. 11, the photoelectric converter 14 and band-pass filter11 may both be provided in plurality. With this arrangement, providedthat the particular wave number of the band-pass-filter 11 a is providedwith a wave number to absorb infrared radiation due to metal oxide whilethe particular wave number of the band-pass-filter 11 b is provided witha wave number to absorb infrared radiation due to carboxylic acid, thetest sample can be analyzed for metal-oxide content and carboxylic-acidcontent.

As shown in FIG. 12, a rotary member 30 including a plurality ofband-pass filters 11 may be provided on the optical axis of the lightsource 10, between the light source 10 and the plate 12. The rotarymember 30 is arranged to place any one of the band-pass filters 11 ontothe optical axis of the light source 10, and to rotate depending uponthe command from the control section 15, thus changing over theband-pass filter 11 placed on the axis.

In this arrangement, by providing the band-pass filters 11 of the rotarymember 30 respectively with different particular wave numbers, it ispossible to detect infrared radiation at a different wave numberreflected from the solder material 13. This makes it possible to analyzethe test-sample solder material 13 for metal-oxide content,carboxylic-acid content and carboxylate content by one test operation.

Meanwhile, each band-pass filter 11 of the rotary member 30 may includean optical filter, that transmits infrared radiation at a reference wavenumber, explained in example 1. The photoelectric converter 14 is causedto detect the intensity at the reference wave number of the infraredradiation reflected from the comparative sample (fourth intensity) andthe intensity at the reference wave number of the infrared radiationreflected from the test sample (third intensity). Furthermore, bycausing the control section 15 to operate equations (61)-(64) and(71)-(78) explained in example 1, it is possible to output correctedintensity difference, intensity ratio, absorbance difference andabsorbance ratio.

The arrangement can be made as shown in FIG. 13.

In a FIG. 13 solder material test apparatus 100, the plate 12 includes alight-transmissive region (ZnSe, or the like) 12 a where light isallowed to transmit through the both surfaces. A solder material 13 isplaced on the light-transmissive region 12 a at one surface of the plate12.

A light source 10, a rotary member 30 and a photoelectric converter 14are arranged in positions opposed to the other surface of the plate 12,wherein mirrors 40, 45 are arranged. Specifically, the rotary member 30and the mirror 40 are arranged in this order on the optical axis of thelight source 10, in a direction along the light traveling from the lightsource 10. The mirror 40 is arranged to reflect the light, illuminatedfrom the light source 10 through the rotary member 30, into a directiontoward the light-transmissive region 12 a. Furthermore, the mirror 45 isarranged to reflect the light, from the light-transmissive region 12 a,into a direction toward the photoelectric converter 14.

According to this arrangement, the band-pass filter 11 included in therotary member 30 permits only infrared radiation at a chosen wave numberof the light emitted from the light source 10. The transmitted infraredradiation is guided to the mirror 40. The infrared radiation isreflected upon the mirror 40 and guided to the light-transmissive region12 a, to reach the solder material 13 through the light-transmissiveregion 12 a. The infrared radiation reaching the solder material 13 isreflected thereupon and guided to the mirror 45 through thelight-transmissive region 12 a. The infrared radiation guided to themirror 45 reflects upon the mirror 45 and enters the photoelectricconverter 14. Due to this, the photoelectric converter 14 is allowed todetect the intensity of the infrared radiation reflected the soldermaterial 13.

Meanwhile, the solder material test apparatus 100 shown in FIG. 12 canbe modified for in-line analysis application. For example, a soldermaterial test apparatus 100 shown in FIG. 14 is for in-line analysisapplication, i.e. for the purpose of in-line-analyzing the deteriorationdegree of a solder material being used in a printing process on aprinted-circuit-board production line.

In FIG. 14, a solder material test apparatus 100 is provided close to aprinter 200 for a printed board.

The printer 200 includes a board 201 printed with a solder material, ametal mask 202 arranged on the board 201 and cut with a wiring pattern,a solder material 13 placed on the metal mask 202, a squeegee 203 formoving the solder material 13 while pushing it, and a controller 204 fordrive-controlling the squeegee 203.

In the solder material test apparatus 100, there are provided an opticalfiber 51 for guiding the infrared radiation transmitting through theband-pass filter 11 of the rotary member 30, and an optical fiber 50 forguiding the infrared radiation reflected from the solder material 13 tothe photoelectric converter 14.

According to this arrangement, the infrared light exiting the lightsource 10 and transmitted through the rotary member 30 is illuminated tothe solder material 13 on the printer 200 through the optical fiber 51.The infrared light is reflected by the solder material 13 and guided tothe photoelectric converter 14 through the optical fiber 50. Due tothis, the solder material test apparatus 100 is allowed to measure thesolder material 13, as a sample, for the intensity of infrared radiationreflected from the solder material 13 or infrared radiation absorbanceto same, and hence to analyze, in-line, the solder material 13 fordeterioration degree.

Meanwhile, the solder material test apparatus 100 and printer 200 shownin FIG. 14 can be modified as in FIG. 15.

In the printer shown in FIG. 15, the squeegee 203 is formed with alight-transmissive region (ZnSe or the like) 203 a where light isallowed to transmit through both surfaces. A solder material 13 isplaced on one side of the squeegee 203.

In the solder material test apparatus 100, there are provided opticalfibers 150, 151. The optical fiber 151 is to input therein the infraredradiation transmitted through the band-pass filter 11 of the rotarymember 30 and allows the infrared radiation to exit onto thelight-transmissive region 203 a at its other surface of the squeegee203. The optical fiber 150 is to input the light from thelight-transmissive region 203 a and guide the light to the photoelectricconverter 14.

According to this arrangement, the infrared radiation exiting the lightsource 10 and transmitted through the rotary member 30 is illuminatedonto the light-transmissive region 203 a at its other surface of thesqueegee 203 through the optical fiber 151. The illuminated infraredradiation reaches the solder material 13 through transmitting thelight-transmissive region 203 a. Furthermore, the infrared radiationreflects upon the solder material 13 and enters the optical fiber 150through transmitting the light-transmissive region 203 a. The infraredradiation entering the optical fiber 150 is guided to the photoelectricconverter 14. Due to this, the solder material test apparatus 100 isallowed to measure, in-line, the solder material 13 placed on theprinter 200, as a sample, for the intensity of infrared radiationreflected from the solder material 13 or infrared radiation absorbanceof the same, and hence to analyze, in-line, the solder material 13 fordeterioration degree.

Meanwhile, as shown in FIG. 15, a metal mask 202 may be structured witha light-transmissive region (ZnSe or the like) 202 a where light isallowed to transmit through both surfaces thereof, to place a soldermaterial 13 on one surface of the metal mask 202. In this structure, theoptical fiber 151 is arranged to allow the infrared light coming fromthe band-pass filter 11 of the rotary member 30 to exit onto thelight-transmissive region 202 a at its other surface of the metal mask202. The optical fiber 150 is arranged to allow the light from thelight-transmissive region 202 a at the other surface of the metal mask202 to enter.

Although the solder material test apparatuses 100 were shown in FIGS. 12to 15 that are capable of conducting an in-line analysis, in-lineanalysis can be realized by structuring a solder-material test apparatus500 as shown in FIG. 16.

As shown in FIG. 16, a solder material test apparatus 500 is arrangedadjacent a printer 300 and structurally includes a light-emittingelement 501, a housing 502, a housing 503, a communication passage 504and a light-receiving element 505.

Of the solder material test apparatus 500, the housing 502 is adjacentthe printer 300, to communicate between the interiors of the housing 502and the printer 300. Furthermore, the interiors of the housings 502, 503communicate together by the communication passage 504.

The printer 300 is for printing a solder material on a circuit board.Within the printer 300, there is arranged a board 300 a in a state whereprinting is being performed. A metal mask 300 b is arranged on the board300 a while a solder material 300 c is arranged on the metal mask.

A light-emitting element 501 is a light source to emit light to thesolder material, which employs any one of a ceramic light source, ahalogen lamp, an LED (light-emitting diode) and a semiconductor laser(laser diode), for example.

The housing 502 is structured with a light-introducing hole (not shown)provided adjacent the light-emitting element 501 in a manner opposingthe emitting surface of the light-emitting diode 501 and for introducingthe light emitted from the light emitting element 501 to the inside.Within the housing 502, there are arranged mirrors 502 a, 502 b, 502 cand 502 d.

The mirror 502 a is an optical means that is arranged opposed to theemitting surface of the light-emitting surface 501 through thelight-introducing hole and for receiving the light emitted from thelight-emitting element 501 and reflecting the light toward the mirror502 b. The mirror 502 b is an optical means that receives the lightreflected by the mirror 502 a and reflects the received light to thesolder material 300 c inside the printer 300. The mirror 502 c is anoptical means that receives the light reflected from the solder material300 c and reflects the received light to the mirror 502 d. The mirror502 d is an optical means that receives the light reflected by themirror 502 c and reflects the received light to an interior of thehousing 503 through the communication passage 504.

The light-receiving element 505 is, say, a photoelectric converter usingan MCT, which is arranged on the exterior wall of the housing 503, toproject its light-receiving part in the interior of the housing 503.

Within the housing 503, there are arranged a diffraction grating 503 aand a mirror 503 b.

The diffraction grating 503 a is an element that diffracts the lightreflected from the mirror 502 d of the housing 502. Of the light, aparticular wave number of infrared light is diffracted to the mirror 503b. The mirror 503 b is an optical means that receives the infraredradiation diffracted by the diffraction grating 503 a and reflects theinfrared radiation to the light-receiving part of the light-receivingelement 505.

According to the above arrangement, the light exiting the light-emittingelement 501 is illuminated to the solder material 300 c through themirror 502 a, 502 b. Due to this, there is light reflection from thesolder material 300 c, the reflection light is guided to the diffractiongrating 503 a through the mirror 502 c, 502 d.

Furthermore, the diffraction grating 503 a diffracts the particularwave-number band of infrared light from the mirror 502 d to the mirror503 b. The mirror 503 b guides the infrared radiation to thelight-receiving part of the light-receiving element 505. Due to this, ofthe light reflected by the solder material 300 c in the printer 300, aninfrared radiation can be guided to the light-receiving part of thelight-receiving element 505, thus enabling in-line analysis.

The invention is not limited to the embodiments described above but canbe modified in various ways within the scope of the invention. Theembodiments, obtained by properly combining the technical meansdisclosed in the embodiments, are included in the technical scope of theinvention.

Incidentally, the control section 15 in the embodiment can be realizedby executing the program stored in the storage means such as ROM (readonly memory) and RAM due to the operation means such as the CPU andcontrolling the input means such as a keyboard, output means such as adisplay or the communicating means such as an interface circuit.Accordingly, by merely reading a recording medium storing the programand executing the program due to a computer having those means, thevarious functions of and processing in the control section 15 can berealized. Meanwhile, by recording the program on a removable recordingmedium, the various functions and processes can be realized on a desiredcomputer.

The recording medium may be a program media such as a memory not-shown,e.g. ROM, because to be processed by the microcomputer, or a programmedia that, although not shown, a program reader is provided as anexternal storage device so that reading is possible by inserting therecording medium therein.

In both cases, the program stored is preferably structured executable byaccessing from a microprocessor. Furthermore, even if the program can bedownloaded from the network, it is desirable that the download programis assumed previously stored in the apparatus beforehand or the downloadprogram is installed by another recording medium.

Meanwhile, as the program media, there is a recording medium structuredseparable from the main body which recording medium, etc. fixedlycarries a program including those based on a tape, e.g. a magnetic tapeor a cassette tape, a disk, e.g. a magnetic disk including a flexibledisk, a hard disk or a CD/MO/MD/DVD disk, a card, e.g. an IC card(including a memory card), or a semiconductor memory, e.g. a mask ROM,an EPROM (erasable programmable read only memory), an EEPROM(electrically erasable programmable read only memory) or a flash ROM.

Meanwhile, provided that in a system structure connectable with acommunication network including the Internet, preferred is a recordingmedium fluidly carrying a program in a manner downloading a program froma communication network.

Furthermore, where downloading a program from a communication network inthis manner, the downloading program preferably is stored in the presentapparatus in advance or installed from a separate recording medium.

The solder material test method and apparatus of the invention is suitedas a method and apparatus that conducts a test of a pasty soldermaterial for use in a printing process on a print board production line,but can be broadly applied generally to the well known solder materialswithout limited to such a pasty solder material.

1. A solder material test method including: a first detecting step ofdetecting a first intensity at a particular wave number of infrared rayreflected from a test-sample solder material by illuminating light tothe test-sample solder material; and a test step of testing adeterioration degree of the test-sample solder material relatively to acomparative-sample solder material, depending upon the first intensitydetected.
 2. A solder material test method according to claim 1, whereinthe particular wave number is included in a range of 520 cm-1 to 700cm-1.
 3. A solder material test method according to claim 1, wherein theparticular wave number is included in a range of 1270 cm-1 to 1430 cm-1.4. A solder material test method according to claim 1, wherein theparticular wave number is included in a range of 1500 cm-1 to 1650 cm-1.5. A solder material test method according to claim 1, wherein theparticular wave number is included in a range of 1665 cm-1 to 1730 cm-1.6. A solder material test method according to claim 1, wherein theparticular wave number is included in a wave number band that aninfrared ray is to be absorbed by a metal oxide contained in the soldermaterial.
 7. A solder material test method according to claim 6, whereinthe metal oxide is tin oxide.
 8. A solder material test method accordingto claim 1, wherein the particular wave number is included in a wavenumber band that an infrared ray is to be absorbed by a salt containedin the solder material.
 9. A solder material test method according toclaim 8, wherein the salt is carboxylate.
 10. A solder material testmethod according to claim 1, wherein the particular wave number isincluded in a wave number band that an infrared ray is to be absorbed byan acid contained in the solder material.
 11. A solder material testmethod according to claim 10, wherein the acid is carboxylic acid.
 12. Asolder material test method according to claim 1, further comprising asecond detecting step of detecting a second intensity at the particularwave number of infrared ray reflected from the comparative-sample soldermaterial by illuminating light to the comparative-sample soldermaterial, and wherein the test step of testing a deterioration degree ofthe test-sample solder material relatively to the comparative-samplesolder material, depends upon both the first and second intensitiesdetected.
 13. A solder material test method according to claim 12,wherein the test step is to determine a difference between the firstintensity and the second intensity.
 14. A solder material test methodaccording to claim 13, wherein a reference wave number is different inwave number from the particular wave number, the first detecting stepbeing to detect further a third intensity at the reference wave numberof infrared ray reflected from the test-sample solder material, thesecond detecting step being to detect further a fourth intensity at thereference wave number of infrared ray reflected from thecomparative-sample solder material, the test step correcting at leastany of the first and second intensities depending upon a differencebetween the third and fourth intensities.
 15. A solder material testmethod according to claim 12, wherein the test step is to determine aratio of the first intensity and the second intensity.
 16. A soldermaterial test method according to claim 12, wherein the test step is todetermine a first infrared ray absorbance at the particular wave numberto the test-sample solder material depending upon the first intensity,and a second infrared ray absorbance at the particular wave number tothe comparative-sample solder material depending upon the secondintensity, thereby determining a difference between the first infraredray absorbance and the second infrared ray absorbance.
 17. A soldermaterial test method according to claim 16, wherein a reference wavenumber is different in wave number from the particular wave number, thefirst detecting step being to detect further a third intensity at thereference wave number of infrared ray reflected from the test-samplesolder material, the second detecting step being to detect further afourth intensity at the reference wave number of infrared ray reflectedfrom the comparative-sample solder material, the test step being todetermine a third infrared ray absorbance at the reference wave numberto the test-sample solder material depending upon the third intensity,and a fourth infrared ray absorbance at the reference wave number to thetest-sample solder material depending upon the fourth intensity, therebycorrecting at least any of the first and second infrared ray absorbancesdepending upon a difference between the third infrared ray absorbanceand the fourth infrared ray absorbance.
 18. A solder material testmethod according to claim 12, wherein the test step is to determine afirst infrared ray absorbance at the particular wave number to thetest-sample solder material depending upon the first intensity, and asecond infrared ray absorbance at the particular wave number to thecomparative-sample solder material depending upon the second intensity,thereby determining a ratio of the first infrared ray absorbance and thesecond infrared ray absorbance.
 19. A solder material test apparatuscomprising: a light source that illuminates light to a test-samplesolder material and a comparative-sample solder material; intensitydetecting means that detects a first intensity at a particular wavenumber of infrared ray reflected from the test-sample solder materialdue to illumination of the light; and control means that outputs adeterioration parameter indicative of a comparative deterioration degreeof the test-sample solder material relatively to the comparative-samplesolder material.
 20. A computer-readable recording medium storing aprogram for use with the solder material test apparatus of claim 19, theprogram when executed by a computer of the test apparatus causing thecontrol means to perform the process of outputting the deteriorationparameter indicative of the comparative deterioration degree of thetest-sample solder material relatively to the comparative-sample soldermaterial.
 21. A solder material test apparatus according to claim 19,wherein the intensity detecting means further detects a second intensityat the particular wave number of infrared ray reflected from thecomparative-sample solder material due to illumination of the light. 22.A solder material test method comprising: detecting a first intensity ata particular wave number of infrared ray reflected from a test-samplesolder material; and testing a deterioration degree of the test-samplesolder material depending upon the first intensity detected.
 23. Asolder material test apparatus comprising: an intensity detector thatdetects a first intensity at a particular wave number of infrared rayreflected from a test-sample solder material; and a controller thatoutputs a deterioration parameter indicative of a deterioration degreeof the test-sample solder material based on the first intensitydetected.